Febrtary. 1907 1 



KNOWLEDGE & SCIENTIFIC NEWS. 



43 



CORRESPONDENCE. 



Phenomenal Sunsets. 



To the Editors of " Knowledge & Scientific News." 



Sirs,— On Mondav, Julv 11, 1904, the sun set at 8.13, in 

 a clear sky in the west, though in the south-east a heavy 

 Ihunderstorm was worlcing up. 



.\bout 8.30 p.m., from a light orange glow, there issued 

 five distinct bands of light of a pale salmon-pink colour, 

 which radiated like the spokes of a wheel from the sun, 

 being definitely separated' by five corresponding bands of 

 pale blue. 



The phenomenon lasted for nearly an hour, the bands 

 graduallv fading away. 



The same night a violent thunderstorm broke over Ex- 

 mouth. 



On Mondav, Julv iS, a similar sunset occurred, though in 

 a modified form, which I saw from Okehanioton, but the 

 " bands " were reduced in number, though they had in- 

 creased in width. 



The following day a heavy thunderstorm broke over the 

 town. 



I saw a tliird sunset a few days after, which was limited 

 to one broad band of salmon-pink light, slightly inclined tc 

 the right of the sun. 



About the same time thunderstorms and heavy rains oc- 

 curred in Paris, and a remarkable phenomenon was seen 

 in the sky on the morning of July 25, between nine and ten 

 o'clock, numerous coloured circles appearing round the 

 sun, like haloes. 



Faithfullv vours, 



C. S'OMERVILLE W.\T.SO\. 



Battersea Park, S.\\'. 



Basaltic Columns. 



To the Editors of " Know i.i;noE & Sc ientific News." 

 .Sirs, — .May I refer those who are interested in the forma- 

 tion of concretionary masses from organic nuclei to a com- 

 munication on the subject which appeared in the (Icoloqieal 

 Maiaziiie of August, 1892? I have not, as yet, had reason 

 to change the views expressed therein. 

 Vours very faithfullv, 



cecil'c.vrls-wii.son. 



Royal Societies Club, S.W. 



The "Flight" of Flyingr Fishes. 



'I'o tiic Editors of " Knowi.edc.e .V Scientuu- News." 

 -Sirs, — The question of the flight — so called— of living 

 fishes is brought up again by the interesting notice of Colonel 

 Dunford, who has not, however, in my opinion, made out 

 his case. During twenty years passed at sea, and at inter- 

 vals since then, I have soeci.-dly studied this mailer, and 

 I am convinced that the fish does not, and cannot. Ilv as 

 birds do. 



The flving fish projects itself into the air by means of its 

 powerful tail, and it is sustained there, often for a consider- 

 able time, by the extension of its large pectoral fins. A 

 rise in the " flight " may sometimes be noticed, but that 

 is merelv due to a heave given by the air forced up by a 

 wave crest. The fish, which apparently floats in the air 

 at an angle of 35° with the sea level, will be seen to fall 

 into the water, but instead of getting submerged, it 

 receives a fresh impetus and again projects itself upwards. 

 The active little anral fins assist the tail, but the pectoral 

 fins are incapable of other movement than the fore and aft 

 motion, which exiends them when the fish rises from the 

 water, and folds them close to the body when it swims in 

 the sea. 



In a calm sea flying fish are seldom noticed out of the 

 water, and when they are the " flight " is extremely short, 

 nothing more than a jump, in fact. As a rule, the fish 

 flics up against the wind ; should it catch them sideways they 

 go off at a tangent, and a breath of air from an unexpected 

 quarter will often turn them right over. 



I had a flving fish alive for a time, and was able to study 

 the motion of the fins in water. Out of water, the pectoral 

 fins soon get quite dry, a fact which would of itself be a 

 bar to real flight. 



It is useless to look for information which mipht be 

 turned to practical application in the construction of aero- 

 machiues by the observation of the movements of flving 

 fishes. It is, however, quite possible that much mi'rht be 

 learned from observations of the flight of the albatross and 

 kindred birds. 



Faithfully yours, 



D. WILSON-BARKER, R N.R. 



H.M.S. JTorcrsfer, Greenhithe. 



Average Rainfall. 



To the Editors of " Knowledge &. Scientific News." 



.Sirs, — Assuming the rainfall during the first six months 

 of the year has far exceeded the average, is it not fair argu- 

 ment to assume at the beginning of the second six months 

 that the remaining rainfall for the year will be deficient? 



Faithfullv vours, 



R. M. 

 [From an analvsis of the Greenwich rainfall records, for 

 the 91 years 1815-1905, it appears that the rainfall for the 

 first half of the year was above the average on 43 occasions ; 

 of these, the rainfall of the succeeding six months was above 

 the average on 20 occasions, but below it on 23. There 

 does not seem to be any reasonable data for founding a 

 forecast of the coming season from these figures. — W.M.I 



Brakes. 



To the Editors of " Knowlkix.e & Scientific News." 



Sirs, — The action of railway brakes was investigated 

 at considerable length in a paper published a few years ago 

 by Professor A. Sommerfeld, of the Technischc Hochschule, 

 .\achen. 



I cannot lay hands on my copy at the present instant, and 

 should, therefore, not have referred to the matter hut for 

 the very inconclusive arguments used in the discussion !n 

 Vdur columns. .\ reference to the paper appeared in Kafiit-'. 

 at the time, and I have no doubt Professor SommerfeiJ 

 would send a reprint to anyone interested in the matter. 



A complete investigation requires account to be taken of 

 the differences which exist between the co-eflicients of rolling 

 and sliding friction, and the fact that the co-eftlcient of 

 sliding friction depends on the relative velocity of the parts 

 ihat ore sliding on one another. These dilTerences arc not 

 mentioned in elementary text-books, and the data requiro-J 

 for solving the problem are necessarily based on the results 

 of experiment. I am practically certain that Professor Sont- 

 metfeld found that the maximum efliciency was not in 

 general obtained when the wheels were locked. 



G. 11. BR^.\N. 



